Roger Thompson

Development of Real-Time Mine Road Maintenance Management System Using Haul Truck and Road Vibration Signature Analysis

The unpaved road network of a surface mine is extensive, comprising numerous roads of varying construction and material qualities with highly variable traffic volumes. Existing haul road maintenance management systems (MMSs) work well for predictable traffic volumes, but for complex mine road networks, the MMS becomes onerous and results in suboptimal road maintenance strategies, with the attendant increase in total road-user costs and reduction in service. A real-time MMS was thus sought to overcome the deficiencies of existing systems for mine roads. Because most large mines operate trucks with onboard diagnostic data collation, linked through a centralized communication and Global Positioning System backbone, it was proposed that road condition could be monitored on a real-time basis through onboard vibration signature analysis. A real-time mine haul road MMS was developed. Mine road maintenance practices were reviewed. The real-time system architecture was devised, and a field trial was conducted of onboard vibration signature assessment. Trial results were evaluated in the light of road defect signature recognition, analysis, signature repeatability, and system limitations. This approach is applicable to other situations, such as a network of district roads, subject to an analysis of economic feasibility. The conclusion is reached that modern technology has the potential to apply maintenance as and where needed, with possible reductions in authority cost and an improvement in service provided to road users.

MANAGEMENT OF UNPAVED ROAD NETWORKS ON OPENCAST MINES

In surface mining operations, ultra-heavy-haul trucks apply axle loads in excess of 200 t, but the daily load repetitions are low. Road networks for these vehicles have historically been designed empirically, relying heavily on local experience. Increasing vehicle sizes have resulted in unwarranted deformations and excessive maintenance requirements. There was thus a need to consider the transportation problem holistically, taking into account construction and maintenance costs as well as vehicle operating costs. Most opencast mines in South Africa are private endeavors, and all savings will benefit the company. A research project was undertaken in South Africa to develop a management system that takes into account different design factors. The various components of the management system are presented, and the value of its application is demonstrated through case studies. The structural design system, the pavement deterioration system, and the maintenance effectiveness are discussed. The components are then combined to provide total transportation costs and the appropriate maintenance regime to minimize total transportation cost. The system has been applied on several mines, and distinct benefits have been derived. The improved structural design of a new road resulted in a 29 percent savings in construction costs, compared with the tendered price of the empirically designed structure. In addition, improved wet weather trafficabililty was noted. Mines have also used the system as a motivation for improved maintenance equipment and strategies because significant benefits were apparent from the adoption of the maintenance management system.

Condition-Triggered Maintenance for Mine Haul Roads with Reconstructed-Vehicle Response to Haul Road Defects

The management of unpaved mine road networks—characterized by high axle loadings, low traffic volumes, variable materials and construction quality, and rapid rates of deterioration—is often inadequate. This situation results in either overmaintenance of the road or failure to recognize significant deterioration, which both lead to the application of suboptimal road maintenance strategies with the attendant increase in total road-user costs. A real-time condition-triggered maintenance management system was identified as a solution, in which onboard monitoring of vehicle dynamic response to road condition forms the basis of road defect recognition and maintenance response. A practical approach to road defect reconstruction using measured truck response is presented. Initially, the application context is introduced, then the field testing program is described, in which data sets were generated that served as the basis for mathematical modeling of the truck response. A modeling approach utilizing the concept of independent front suspension dynamic equilibrium is described as the basis for road defect recognition. On the basis of measured suspension forces and the acceleration of the unsprung mass, the approach to tire force and road defect reconstruction is presented. It is concluded that the methodology developed enables reconstruction of road defect geometries with an accuracy sufficient to allow specific types and dimensions of defects to be recognized for the purpose of road maintenance. By extending the methodology to public unpaved roads, maintenance could be applied as and where needed with a resultant reduction in authority cost and improvement in service provided for the road user.

A GPS Based System for Minimizing Jolts to Heavy Equipment Operators

When two pieces of heavy equipment interact, jolting and jarring can occur. During haulage truck loading for example, there is a chance that the operator of one or both pieces of the equipment will experience jolting and jarring. Additionally, a jolt can occur when an off highway equipment operator drives over a road defect or inadvertently strikes a berm. Aside from the operators, there is seldom anyone else that witnesses the interaction and can accurately describe the extent of the jolting. This makes it difficult for h alth and safety managers to address jolting and jarring. The devices and software described in this paper constitute a method for installing black boxes called Shox Boxes onboard equipment that already have a GPS system onboard. The resulting configuration provides an objective assessment of jolting and a chance to determine the root causes of it. The Shox Box system reviews data in real time, onboard the vehicles, 24 hrs a day, and sends pertinent information via radio to a central database. The data generated shows whether jolts are above or below a supervisor defined target value for the equipment and the tasks being performed. This allows health and safety personnel to demonstrate safe operation of heavy equipment and recommend proactive actions to maintain jolting within a reasonable range.